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Effects of 1-or 3-h scotophase-interrupting lights applied midway through the 16 h dark period on diapause incidence of T. urticae and T. kanzawai with blue, green, orange, and white OLEDs that were turned on at 7.5 and 6.5 h after the start of the dark period for 1-and 3-h interruptions, respectively. PFD was set at 0.2, 2, and 20 µmol m −2 s −1 . Data were arcsine-transformed before analysis. Means followed by different letters are significantly different at P < 0.05 by Tukey's HSD test after ANOVA. Analyses were separately carried out for 1-and 3-h interruptions.
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Tetranychus urticae Koch and T. kanzawai Kishida enter facultative diapause in response to short-day photoperiods. To determine the effect of various colors of light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) on diapause induction, both species were reared under different photoperiods at 18°C and 2.0 W m⁻² light intensity, in...
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Citations
... Worthwhile, blue LEDs and OLEDs at 3-h scotophase interruption and even at low light intensity, were able to inhibit diapause induction in both mites (Amini et al.,2016). Besides, diurnal and nocturnal species are attracted to yellow color even it was represented in the sticky traps, pan traps or even at light traps supplied with LEDs ( Shimoda and Honda,2013). ...
... Worthwhile, blue LEDs and OLEDs at 3-h scotophase interruption and even at low light intensity, were able to inhibit diapause induction in both mites (Amini et al.,2016). Besides, diurnal and nocturnal species are attracted to yellow color even it was represented in the sticky traps, pan traps or even at light traps supplied with LEDs ( Shimoda and Honda,2013). ...
Metabolic resistance of pesticides is the target of green technologies in order to be reduced successfully in family Tetranychidae. Resistant strains of some tetranychid mites to fenvalerate (pyrethroids) and spinosad (spinosyns) were exposed to certain colors of light emitting diodes (LEDs). Tetranychus urticae, Panonychus ulmi and Oligonychus mangiferus, were resistant to fenvalerate (pyrethroids) and spinosad (spinosyns) after selection pressure for 40 generations. Resistance ratios (RRs) were reduced after exposure to white LEDs to be lower to fenvalerate with (22.22, 31.29 and 33.76-folds) and to spinosad with (24.53, 27.08 and 46.22-folds), respectively. Furthermore, red LEDs were able to record RRs to fenvalerate with 24.56,21.50 and 34.64-folds and to spinosad with 25.06,20.41 and 29.80-folds, for the same arrangement of resistant strains of mites. LEDs can do their actions by increasing reactive oxygen scavengers (ROS) gradually. The highest increase of the reactive oxygen scavengers (APX) was recorded in the case of fenvalerate resistant strain of T.urticae with 5.08-folds, which exposed to white LEDs. While the red LEDs caused the highest APX ratio in the case of spinosad resistant strain of P.ulmi with 3.03-folds. They have been regarded highly and led to acquire susceptibility to pesticides again. Results are elevating the hope to decrease metabolic resistance with the available and the useful resource of eco-friendly implements to keep the ecosystem.
... Insects undergo diapause through a dynamic process consisting of several successive phases including diapause induction, maintenance, termination, postdiapause quiescence and post-diapause development (Koštál 2006). All these phases are strongly affected by photoperiod and temperature (Tauber et al. 1986;van Houten et al. 1988;Amini et al. 2016). ...
Previous studies on the spider mite Eotetranychus smithi Pritchard & Baker have shown that diapause in eggs is induced by low temperature alone and that females developed at ≤ 17.5 °C laid diapause eggs, regardless of the photoperiod. In this study, diapause eggs were kept at 5 °C and a photoperiod of 16L:8D for 0–120 days and then maintained at 25 °C to know the effect of chilling on diapause termination. Diapause eggs mostly hatched when they were maintained at 25 °C after chilling for 30–90 days at 5 °C, which suggests that diapause termination is favored by low temperatures. To clarify the hatching conditions after diapause termination, diapause eggs kept at 5 °C for 45 days were subsequently maintained at various constant temperatures (from 15 to 25 °C) under a long-day photoperiod (16L:8D). The hatchability at all temperatures tested was high (> 90%) and did not significantly differ among the high temperatures. Duration of embryonic development was shorter with increasing warming temperature after chilling. The lower thermal threshold (t) and thermal constant (k) for post-diapause egg development were 10.5 °C and 76.9 degree-days, respectively. Females, which developed from diapause eggs that were chilled at 5 °C for 45 days and then maintained at 15 °C, laid only non-diapause eggs, which indicates that they were prevented from re-entering diapause even under diapause-inducing conditions (15 °C). Thus, temperature is the main factor to control diapause termination and post-diapause development, which has also been found for other spider mites that enter diapause at the egg stage.
... The two-spotted spider mite, Tetranychus urticae Koch, which infests more than 1100 species of host plants, is the most important polyphagous spider mite and a vital pest in temperate regions for many crops (Hamedi et al. 2011;Amini et al. 2016;Migeon & Dorkeld 2016). Although biological control of T. urticae has been proven to be successful in many crops growing in greenhouses, acaricides have always played the central role in its control in field crops, owing to their lower cost and strong effects (Sanderson & Zhang 1995;Van Leeuwen et al. 2010;Jafari et al. 2016). ...
Traditional estimating only by measuring the lethal effect of acaricides may underestimate the total effects of acaricides on the pest mites. In order to investigate the sublethal effect of bifenazate on life history and population parameters of the two-spotted spider mite, Tetranychus urticae Koch, the newly emerged females were treated with two lethal concentrations of bifenazate: LC10 (4.92 μg/mL) and LC20 (8.77 μg/mL). Subsequently, the development and fecundity of the progeny generations were observed. Compared to the control, exposure to the 10% lethal concentrations (LC10) and LC20 of bifenazate severely affected the parental generation of T. urticae, including survival rate (reduced 9% and 13%), oviposition period (reduced 77.6% and 83.1%), fecundity per female (decreased 89.2% and 76.9%) and longevity (decreased 79.2% and 83.1%). Besides, the population parameters of the progeny generation from the treated females were also investigated. The results showed that the progeny generation had lower intrinsic rate of increase (rm) and finite rate of increase (λ), longer mean generation time (Tc) compared to the control. The results suggested that the sublethal effects of bifenazate on population growth of T. urticae were significant, and the results of this study could be used as a guide for the rational use of bifenazate in the field for better managing pest mites.
We investigated feeding and fecundity of the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), on leaves of cucumber (Cucumis sativus) seedlings that had been acclimatized to different light intensities. Based on these data, we analyzed the relationships between mite performance (feeding and fecundity) and leaf properties. The cucumber seedlings were grown in controlled-environment chambers under different light intensities at a photosynthetic photon flux density of 50, 100, 150, 300, or 450 µmol m− 2 s− 1 until the first true leaves had expanded. Adult females were released on the adaxial surfaces of excised leaf samples from the seedlings of each treatment group and held under standardized light intensity (200 µmol m− 2 s− 1). Fecundity and leaf damage area increased and decreased, respectively, as the acclimatization light intensity increased, indicating indirect effects of light intensity on feeding and fecundity through changes in the host leaf properties. Leaf mass per area (LMA) and photosynthetic capacity, which increased as the acclimatization light intensity increased, was positively related to the fecundity, but was negatively related to the leaf damage area. The higher LMA and photosynthetic capacity results in an increased amount of mesophyll per unit leaf area. This would allow the mites to feed efficiently from a limited area, which may explain the increased fecundity on these leaves.
BACKGROUND
Two‐spotted spider mite (TSSM), Tetranychus urticae Koch is a serious agricultural pest and has developed high levels of resistance to many acaricides. Hence, screening new acaricides is important in the control of TSSM. Fluralaner, a novel isoxazoline, has high activity against agricultural and ectoparasitic pests; however, little information is available about its effects on agricultural mites. Lethal and sublethal effects of fluralaner towards TSSM eggs and female adults were therefore evaluated in this study.
RESULTS
Fluralaner exhibited higher activity towards TSSM female adults (LC50, 0.49 mg L⁻¹) compared with commercial acaricides including fenpyroximate, pyridaben and hexythiazox, and also excellent activity towards eggs (LC50, 0.36 mg L⁻¹). The results of a sublethal effect study showed a significant reduction in the duration and fecundity of female adults with increases in the tested concentrations. The net reproductive rate (R0) decreased to 67.34 ± 3.96 and 50.29 ± 3.40 offspring per individual in LC10 and LC30 treatments compared with control (108.31 ± 7.61 offspring per individual). The intrinsic rate of increase (r) and finite rate of increase (λ) in the controls (0.30 and 1.36 d⁻¹) were significantly higher than in the LC30 treatment (0.25 and 1.29 d⁻¹); whereas, they were almost identical to values for the LC10 treatment. No change in mean generation time (T) was observed at sublethal concentrations treatments.
CONCLUSION
Our results demonstrated that fluralaner has high acaricidal activity and could be considered a potential acaricide for TSSM management. © 2019 Society of Chemical Industry
